Agreed on the net neutrality thing but on a mobile network, I think you'll find it's always been there. For a long time, anything like Skype etc. was dialled down compared to other access, presumably because it's competitive but you could reasonably argue that the real-time requirement isn't suited to what should be "data sent in the gaps" between their own real-time data (i.e. phone calls).
Nowadays, not so much of that goes on, but if I was unhappy I could move to any other provider in seconds. Grab a SIM, slap it in. However, data usage limits are growing all the time (even if you exclude the "unlimited" offers) so it's not really a huge issue at the moment, I feel. Three do a package where only TVPlayer and Netflix are excluded - I can quite easily guess which company most people would go with, whichever one bundles the most. Nobody is going to just subscribe to a service purely on the basis that their ISP doesn't count it against them... it's the other way round, especially on mobile. They'll just move their number to a provider that doesn't penalise them for preferring a particular service.